Analogue and digital

• What is analogue data

  Data that is infinitely variable
• What are analogue signals

  Data that is represented/transmitted in the form of a wave
• What is digital data

  Data that has discrete variables
• What are digital signals

  Data that is transmitted as 1s and 0s and are represented as peaks and troughs
• Explain how analogue to digital conversions (ADC) work (3)

  • Analogue sound samples are recorded by an amplifier
  • amplifier takes samples of analogue sound at frequent and uniform time intervals
  • Each sample is quantised by measuring its wave height and translating it into an integer value
  • integer value is then converted and stored digitally as binary
• Explain how digital to analogue conversion works

  Converts stored binary sound-samples into a physical quantity of smth like voltage of pressure
• What are bitmapped graphics

  An image made up of individual pixels that are represented using sequences of binary digits
• what is resolution


  number of pixels per inch
• How is resolution calculated

  resolution = width x height
• what is colour depth

  number of bits stored for each pixel

  • 2^n different colours a pixel can be
  • more bits = more colour depth = more storage required
• How to calculate the amount of storage required to store a bitmapped image

  storage = resolution x colour depth

  • (width x height) x (2^n)
• What extra data to bitmap files contain

  metadata (information about the bitmap itself)

  • usually at the beginning of the file
  • info like file type, width/height in pixels, colour depth etc